A two-dimensional code and a bar code are used in various fields such as the production field and the medical field. For example, a mark presenting predetermined information like the two-dimensional code allows the information to be read by performing image processing of image data acquired through image capturing performed by a camera. In a reader which reads information of the mark through such image processing, recognition accuracy of the mark is desired to be improved. In regard thereof, in PTL 1 and PTL 2, a distance between the mark and the reader is measured or calculated so as to correct image controlling of the mark, thereby improving recognition accuracy of the mark.